1. Field of the Invention
The present invention relates to a connection structure of a tube arranged in an operation section of an endoscope.
2. Description of the Related Art
Conventionally, endoscopes have been commercialized which are equipped with an insertion portion provided with observation means such as an image pickup device and an ultrasound transducer at a distal end portion and formed in an elongated tubular shape, and an operation section provided with various operation members to which a proximal end of the insertion portion is connected. Among such types of endoscopes, a variety of medical endoscopes are being commercialized and becoming widespread, which are configured to insert the insertion portion into a body cavity of a living body of a patient or the like, acquire an observation image by the observation means, and be able to perform various inspections or treatments on a region such as a lesion in the body cavity of the living body while observing the region using the observation image.
There are various modes of such conventional endoscopes such as one whose insertion portion is introduced from the oral cavity, anus, urethra opening or the like or one whose insertion portion is introduced into the abdominal cavity from a through hole punctured in the body wall in the vicinity of the umbilical region in order to observe the interior of organs which are tubular cavities and tubes in the body, for example, a digestive system organ such as esophagus, stomach, large intestine, duodenum, a urinary system organ such as urethra, ureter, bladder or a respiratory system organ such as trachea, lung.
Furthermore, conventional endoscopes are provided with a treatment instrument insertion channel through which various treatment instruments or the like inserted from a treatment instrument insertion port provided at the operation section can be inserted, and which is made up of an elongated tubular body connected to an air/water feeding apparatus or a suction apparatus connected to the operation section. This treatment instrument insertion channel is inserted and arranged in the insertion portion, has an opening at a distal end portion thereof, and a proximal end portion thereof is connected to a connection member made of a metal member provided in the operation section. This connection member is interposed between the treatment instrument insertion port and the treatment instrument insertion channel and is configured to insert or withdraw the various treatment instruments introduced from the treatment instrument insertion port so as to be able to insert or withdraw the distal end of the treatment instrument from an opening at the distal end of the insertion portion. Furthermore, an air/water feeding tube that extends from the air/water feeding apparatus or a suction tube that extends from the suction apparatus is connected to the connection member.
In the conventional endoscope having such a configuration, the connection member functions as a branching member that branches a tubular path of the treatment instrument insertion channel into a tubular path from the treatment instrument insertion port and a tubular path from the air/water feeding or suction tube. In this way, it is possible to perform treatment on a lesion using the treatment instrument, collect a tissue of the lesion to conduct a biopsy for examining mucous membrane, secretion or the like, and at the same time to send a gas or liquid into the body cavity or perform suction from within the body cavity using the air/water feeding apparatus.
Furthermore, since high resistance is required in recent years as a treatment instrument insertion channel tube used for an endoscope, there is a case where in addition to a tube having a general single layer structure, a tube having a laminated structure such as a tube with a plurality of layers containing elemental wires, for example, a three-layer structure (inner resin layer, net wire layer (intermediate layer) and outer resin layer) is used. Furthermore, in consideration of chemical resistance or the like, and for a reduction of friction with the treatment instrument inserted therein, it is desirable to apply fluorine resin (polytetrafluoroethylene (PTFE)) as a raw material of the inner resin layer. In this case, a resin material other than fluorine resin is used for the raw material of the outer resin layer.
Water tightness or air tightness is preferably secured in a connection region between the connection member (branching member) made of a metal member and the treatment instrument insertion channel tube.
As means for water-tightly or air-tightly connecting the connection region between the metal member and the resin tube, various means are proposed or commercialized such as means disclosed in Japanese Patent Application Laid-Open Publication No. 2000-356291.
The means disclosed in Japanese Patent Application Laid-Open Publication No. 2000-356291 is designed to clamp one end of a tube connected to a tapered resin fastening device by pinching it using a nut-shaped tightening instrument and thus water-tightly connect and hold both parts. As an application example of this means, a connection member that connects a tap water hose and a metal faucet is illustrated.
Furthermore, as other means, means disclosed, for example, in Japanese Patent Application Laid-Open Publication No. 9-229258 is proposed.
The means described in Japanese Patent Application Laid-Open Publication No. 9-229258 is designed to interpose a split ring made of fluorine-based resin (raw material with a low frictional coefficient) between a fastening device and a tapered part when clamping one end of a tube connected to a tapered fastening device by pinching it using a nut-shaped tightening tool.